People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

Headache / Migraine

Headache is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the pain-sensitive structures around the brain. Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea.